The separation of various components from mixtures is commonly performed in the sciences. Chromatography is one of the most common processes used to perform such separation and chromatography methods are well known.
Chromatography processes involve the separation of mixture components by the distribution of the components in a stationary phase and a mobile phase. The stationary phase is typically an immobile packing material in a defined space, such as the interior of a tube. The mobile phase is typically a liquid phase that passes through, over, and/or around the stationary phase. The mobile phase includes a solvent and the components of the mixture to be resolved, which are dissolved in the solvent. The resolution of the components of the mixture from the mobile phase occurs by contacting the stationary phase with the mobile phase, such as is used in HPLC processes.
Positioning of the packing in the steel tube provides channels through which the mobile phase may travel. During its travel through the stationary phase, the mobile phase may react with or interact with the packing materials, thereby separating or resolving the components of the mobile phase.
Stationary phases used with HPLC processes and other solid phase extraction systems include silica-based components, although polymer-based stationary phases have also been developed in both bead and monolith form. Typically, the stationary phase in an HPLC column or other solid phase extraction device includes silica-based or polymer-based beads packed in a column. The columns are typically reusable glass or steel tubes lined with polyethyletherketone (PEEK) that can withstand the back pressures experienced during the separation process. The packing materials may be coated with species that assist in the separation of mixtures, such as C-4, C-8 and C-18. Beads are placed inside these columns by physically packing them into the containing structure. Beads used in polymeric separations typically vary in diameter from 5-50 μm, and are packed in a very dense manner. This dense packing creates very little void volume, creating high column back pressures, often greater than 5000 psi (344.7 bar).
Columns containing a monolithic polymer are formed via in-situ polymerization. Monolithic polymer stationary phases exhibit lower back pressures than polymeric bead stationary phases.
WO 03/022393 teaches using polymer fibers as a stationary phase for chemical separations including liquid chromatography. However, the fibers of this reference are loose capillary-channeled fibers that are drawn through a conventional column, the plurality of fibers colinearly extending the full length of the column.
Improvements to current separation processes such as HPLC and solid phase extraction systems may be desirable.